Need help finding ways to anchor furniture

Where can I buy hardware to anchor furniture to the wall? I got a feeling that my son is going to be a climber, and I want to make sure that I have all the bookcases secured to the wall. I've seen some tethers sold online, but are there any stores that may sell this type of hardware?

If not, any ideas on how I can start securing things? I went to Home Depot to see if I could find any L-brackets but couldn't find anything suitable.

If not, any ideas on how I can start securing things? I went to Home Depot to see if I could find any L-brackets but couldn't find anything suitable.

At Home Hardware, in the section where they have door hinges and other hardware, you can find Stanley corner braces that can be used to anchor furniture. You don't even have to screw them into the furniture, if you just mount a couple of them on the wall right on top of the bookshelf. The horizontal part of the brace will prevent the bookshelf from tipping over. I find them to be very sturdy...much better than the cheap anchor straps Ikea provides with some of their furniture pieces.

(Oops, I forgot that I have other furniture on top of the shelving that I installed these corner braces on. So the braces stay mostly hidden. If there's nothing above your bookshelf, then this kind of brace would be completely visible and you may not like the appearance. The advantage of the Ikea style anchor straps is that they're basically not visible. )